电荷在电场的作用下就会沿着电场的方向移动，这种电荷的定向移动叫（）。
A.电压
B.电流
C.电量
D.电场
参考答案：B
A client, a gravida 3 para 2 at 35 weeks’ gestation, comes in to the antepartum clinic for a check-up. She has been experiencing backaches after standing all day at her job as a grocery clerk. Which of the following exercise would the nurse suggest to relieve backache
A. The pelvic tilt.B. Squatting.C. Stretching.D. Walkin
弹簧的功用是什么？
